This invention relates generally to retractable screen systems for installation across a storm drain inlet, and particularly, to a retractable screen system for installation across a storm drain inlet that is locked in a closed position during dry periods and when water runoff levels are low, and which automatically retracts to an open position when water runoff reaches a predetermined level.
The storm drain system is a vast network of underground pipes and open channels that were designed to prevent flooding of city streets. Rain water and ground water runoff drains from the street into the gutter and enters the storm drain system through an opening in the curb called a storm drain inlet or a catch basin. Curbside storm drain inlets serve as the primary entry point for urban runoff water into the storm drain system.
A storm drain inlet is designed to drain excess rain and ground water from streets, parking lots, sidewalks, and roofs. Storm drains inlets vary in size and design from small residential dry wells to large municipal systems. The storm drain inlets receive water from street gutters on most motorways, freeways and other busy roads. Storm drain inlets are also often found in towns and areas which frequently experience heavy rainfall, flooding, and storms.
Most storm drain inlets are provided with gratings or grids to prevent various large objects from falling into the storm drain system. The bars of the typical gratings are fairly widely spaced so as to not impede the flow of water into the storm drain inlet. As a result, various small objects, including many types of common environmental debris, pollutants, and trash, such as aluminum cans, styrofoam and plastic cups, paper wrappers, plastic bags, etc., regularly fall into the storm drain inlet opening. If not caught by the catch basin, or sump, which typically lies immediately below the grating, these environmental debris and pollutants often end up in the storm drain system and in the body of water to which the storm drain system leads, for example, an ocean, a river, etc.
Various storm drain inlet covers or gates configured to prevent smaller types of environmental debris, trash, and pollutants from entering the storm drain system are known in the art. Typically, such covers are in the form of a plate having a plurality of perforations or a mesh-like configuration designed to block out small objects. Some of the known covers are permanently attached to the storm drain curb inlet opening and stay closed irrespective of water runoff levels. Some examples of such covers are disclosed in, for example, U.S. Pat. No. 4,594,157 to McGowan and U.S. Pat. No. 7,179,371 to Bistline. One disadvantage of such covers is that when debris, trash, or the like accumulate in front of, or attach to these storm drain covers, the openings in the cover are blocked and no longer permit water to drain from the street thereby leading to possible flooding.
Some of the known storm drain covers stay closed to prevent smaller-sized environmental debris, pollutants, and trash from entering the storm drain system during dry periods and periods when water runoff levels are low, but when water flow becomes stronger or when levels rise, water interacts with the mechanical parts of such cover systems and causes the covers to swing open.
When the storm drain covers open, water is permitted to flow unimpeded into the catch basin through the storm drain curb inlet. With the storm drain cover open, debris and trash are permitted to enter the catch basin through the storm drain inlet along with water runoff. However, conventional street sweepers typically collect debris and trash accumulated on the streets and adjacent the storm drain inlets on a weekly basis. Since the storm drain covers are closed during dry and low water level periods, the storm drain covers provide for the removal of a large percentage of debris and trash during street sweeping operations, preventing such trash and debris from entering the storm drain system when the storm drain covers open in response to higher water levels.
Some of the known storm drain cover systems designed to remain closed during dry periods or periods of low water flow to block out environmental debris and pollutants and to open during periods of increased water flow or water levels are disclosed in, for example, U.S. Publication No. 2004/0069697 to Martinez, U.S. Publication No. 2004/0173513 to Nino, U.S. Publication No. 2008/0014021 to Flury, U.S. Pat. No. 6,972,088 to Yehuda, U.S. Pat. No. 7,234,894 to Flury, and U.S. Pat. No. 7,238,279 to Saurenman et al. One disadvantage of such systems is that a large number of complex mechanical components are employed in the mechanism that causes the storm drain cover to open. Systems using a large number of mechanical parts are costly to build, install, and maintain. In addition, the more mechanical parts used in a storm drain cover system, the higher the likelihood that one of the system components breaks or malfunctions.
Additionally, other known retractable screen systems, such as those disclosed in, for example, U.S. Pat. No. 7,467,911 to Flury, utilize springs to control movement of the screen. Springs are disfavored for use in the sewer environment, are difficult to calibrate properly and can fatigue over time, and therefore increase the likelihood of system malfunction.
Thus, there exists a need for a retractable screen system for use with storm drain inlets that is simple in design, includes a relatively small number of parts, and does not depend on complex mechanical interactions to translate the action of water into the rotation of the storm drain cover to the open position.